dma_addr_t sa1100_get_dma_pos (dma_regs_t * regs);
This function returns the current physical (or bus) address for the given DMA channel. If the channel is running i.e. not in a stopped state then the caller must disable interrupts prior calling this function and process the returned value before re-enabling them to prevent races with the completion interrupt handler and the callback function. The validation of the returned value is the caller's responsibility as well -- the hardware seems to return out of range values when the DMA engine completes a buffer.
The regs identifier is provided by a successful call to sa1100_request_dma.